When debugging and repairing circuit boards containing surface-mount components, a connection between the circuit board and auxiliary test equipment is needed to transmit signals between the circuit board and the test equipment. In the past, various interconnect methods were attempted to establish this connection. Such methods included using connector devices which pressed down conductive elements over the leads of the surface-mount component, using devices which soldered conductive elements to the leads of the surface-mount component or to the lands on the circuit board, and using devices which mounted outside the surface-mount component's footprint and provided a pin-and-socket interface.
The devices used in the prior art for establishing interconnection between auxiliary equipment and circuitry using surface-mount components had several drawbacks. First, devices which pressed down over the leads of the surface-mount component typically carried the risk of damaging the component's leads. Second, devices which soldered to the leads of the surface-mount component or to the lands on the user's board had the drawback of slow installation and posed the danger of creating shorts between pins at finer pitches. Lastly, devices which mounted outside the surface-mount component's footprint and provided pin-and-socket interface tied up valuable internal wiring planes as well as necessitated relatively wide spacing between adjacent connections. This limits the density of connections that can be made on the surface of the board.
In addition to these drawbacks, the methods of interconnection in the prior art also had problems when implemented for connecting test equipment to circuit boards containing finer-pitch surface-mount packages. Advances in microprocessing and packaging technology have led to smaller surface-mounted microprocessor components utilizing a greater number of leads with more compact spacing. Today's microprocessor components can contain several hundred leads that are spaced individually less than 0.010 inches apart.
The devices used in the past for connecting test equipment to circuit boards containing coarser-pitch microprocessor components were ineffective for connecting test equipment to circuit boards containing fine-pitch, surface mounted microprocessors. Devices which pressed down over the leads of the microprocessor component had problems with the shorter, smaller, and more closely spaced leads. Solder-on devices were subject to poor solder joints, human error, and the possibility of damaging the microprocessor. In addition, the possibility of creating shorts between leads became more likely. Devices which mount outside the component footprint for the newer, finer-pitch microprocessors still required more space on the circuit board than the designer could afford.
Thus, an electrical connector which is able to establish interconnection between circuitry using surface-mount components on a first circuit board and auxiliary circuitry on a second circuit board without damaging the component leads, creating shorts between the pins of the components, and without occupying an excessive amount of space on the circuit board is needed. This connector must be able to interface with surface-mount component connections on a circuit board where the component leads are spaced less than 0.010 inches apart. This connector must also be able to be implemented mechanically by a user without requiring much effort.
The present invention overcomes the drawbacks of the prior art by providing an electrical connector which utilizes signal wiring coupled to conductive bumps of fine geometry and reliable alignment techniques. Since electrical contact is established with the electrical connector through electrical contact pads on both the first and second circuit boards, the present invention allows interconnection between circuitry on the circuit boards without requiring the presence of a microprocessor on the first circuit board. This allows the electrical connector to be used with logic analyzer and in-circuit emulator test equipment.
Connections made independent of accessing the leads of the microprocessor allows a single implementation of the present invention to provide interconnection with different microprocessor implementations and packages types. For example, the electrical connector can be implemented with ball grid array (BGA) packages, tape carrier packages (TCP), and high density QFP (HDQFP) packages. The techniques of interconnection implemented by the present invention is also scalable. Additional contact bumps and signal lines can be added to the electrical connector.